Here's why:
* Genetics: The gene for fur color in cats is located on the X chromosome. Females have two X chromosomes, while males have one X and one Y.
* Orange and Black: The genes for orange and black fur are both on the X chromosome. A female cat can inherit one X chromosome with the orange gene and one X chromosome with the black gene, resulting in a calico or tortoiseshell pattern.
* White: The white fur gene is a separate gene and doesn't influence the other colors. It can appear anywhere on the cat's body, even mixed in with the other colors.
So, a three-colored cat is usually a female calico or tortoiseshell cat.
While male cats can also be three-colored, it's much rarer because they only have one X chromosome. This would require a very specific genetic mutation to have both orange and black fur on the same X chromosome.